Conventionally, electric devices, such as electric tools, may be equipped with accumulators (rechargeable storage batteries) in order to operate the devices independently of a supply network. For portable electric devices, lithium-ion storage batteries are often used, which have an advantageous ratio between energy density and weight as well as size. It is conventional to develop storage batteries of electric devices as self-contained and possibly exchangeable units, so-called storage battery packs.
Lawn mowers, for instance, are often designed as electric devices operated with the aid of storage batteries. However, due to the limited energy capacity of conventional storage batteries, such lawn mowers are unable to compete with gasoline-operated lawn mowers as far as output and operating times are concerned. Larger areas cannot be mowed without interrupting the task in order to recharge the storage battery of the lawn mower. Another disadvantage is the high power consumption during longer mowing periods under more difficult conditions such as high or wet grass. This leads to considerable heating of the storage battery, which adversely affects its service life. In addition, the battery pack must first cool down after the exchange before it can be recharged. This makes it necessary to interrupt the work for longer intervals.